1. Field of the Invention
The present invention relates to a socket for electric component for removably holding an electric component, such as an IC package, and connecting it to another electric circuit apparatus, and more particularly, to a socket for electric component which positively secures an electric component in a rigidly connected condition while causing a contact pin or pins to be elastically brought into contact with an electrode surface provided on the bottom of the electric component.
2. Description of the Related Art
Conventional sockets for electric component of this type, especially, a conventional socket for electric component of the open top type has an accommodating part for an electric component in the top, a socket main body to which a plurality of contact pins to be connected to the leads of an electric component accommodated in the accommodating part are attached, and a socket covering which is vertically movably mounted on the top side of this socket main body, and is operated by its vertical movement for clamping the leads of an electric component accommodated in the accommodating part of the socket main body with the contact pins for connection and securing.
With an IC package as an electric component to be connected and secured by means of the conventional socket for electric component of the open top type, a number of leads are arranged in line while being jutted out at both side edge parts of the package main body, or are arranged in line while being jutted out at all the four side edge parts of the package main body. To connect and secure such an IC package to the socket for electric component, the socket covering which is vertically movably mounted on the top side of the socket main body is pressed down to open the contact pins provided at the periphery of the accommodating part of the socket main body, and in this state, the leads of the IC package are accommodated in the above-mentioned accommodating part. Thereafter, canceling the pressing down of the above-mentioned socket covering permits the socket covering to move up with respect to the socket main body, closing the above-mentioned contact pins to thereby clamp the leads of the IC package accommodated in the accommodating part with a prescribed pressing force for connection and securing this IC package to the socket for electric component.
[Patent Document 1] Unexamined laid-Open Patent Publication No. 2000-182738
Nevertheless, with some of the recently available IC packages, an electrode surface made of a metallic piece for heat dissipation, grounding or supplying power is provided on the bottom of the package, in addition to the ordinary leads. To cope with such an IC package, a socket for electric component that is equipped with a separate contact pin for contacting with the electrode surface on the bottom of the package has been demanded. However, a socket for electric component which is capable of meeting this demand by positively connecting and securing an electric component while permitting the separate contact pin to come in contact with the electrode surface provided on the bottom of the electric component has not yet been provided.
When it is intended to realize such a socket for electric component, there arises a problem that, for the above-mentioned IC package having the electrode surface on the package bottom, the separate contact pin must be jutted upward in the vicinity of the central part of the socket main body. Thus when the socket covering is pressed down to open the contact pins provided at the periphery of the accommodating part of the socket main body for accommodating the leads of the IC package in the above-mentioned accommodating part, and when the pressing down of the socket covering is then cancelled so as to cause the socket covering to move up with respect to the socket main body, the contact pins must be closed for clamping the leads of the package to secure them before the upward moving of the socket covering. Otherwise, the above-mentioned separate contact pin would pop up the bottom of the IC package, which would make it impossible to connect and secure the IC package to the socket for electric component.
Therefore, the socket construction must be such that the leads of the IC package accommodated in the accommodating part are clamped by the contact pins for connection and securing before the contacting part of the separate contact pin being brought into contact with the electrode surface of the IC package. Nevertheless, for example, with a socket for electric component for use with an SOP (Small Outline Package), in which the contact pins are provided at the opposed two side edge parts of the accommodating part, or a socket for electric component for use with a QFP (Quad Flat Package), in which the contact pins are provided at all the four side edge parts of the accommodating part, the existence of the numerous contact pins has made it difficult to incorporate a structure for controlling the operation of the above-mentioned separate contact pin.